Unlike the liquid or solid sample, gas sample, when is measured, is fed mainly manually (except online instruments) as the gas sample is more easily lost. Sample feeding is one of the main sources of error of quantitative analysis during gas composition analysis, especially during the manual sample analysis carried by a man. The speed and pressure of sample feeding are different between different operators, and further it is difficult to maintain the consistence between the sample feedings even if by the same operator.
In addition, the sample will go through the steps of collection, transportation and sampling measurement, etc., which are complicated, and most of the steps is implemented by manual work which will introduce a lot of uncertainty. Currently, as one choice, hard bottle is used as a sample bottle to collect and feed sample. The hard bottle is vacuumized before collecting sample, and the sample gas is pressed into the bottle to produce a certain positive pressure in it when the sample is collected. The sample gas is injected into feeding inlet of the equipment under the pressure in the step of sample feeding. However, it is difficult to maintain the pressure in the sample bottle consistent, and different pressures will cause the volume of quantitative ring to be different, which is the leading cause for poor sample repeatability. Further, the container being cleaned incompletely and having poor gas tightness will also affect the results. At present, there has not appeared a kind of low cost, and reliable gas autosampler.